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  <title>使用自然排序算法比较字符串</title>
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  <div id="layout-content"><div id="function.strnatcmp" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">strnatcmp</h1>
  <p class="verinfo">(PHP 4, PHP 5, PHP 7, PHP 8)</p><p class="refpurpose"><span class="refname">strnatcmp</span> &mdash; <span class="dc-title">使用自然排序算法比较字符串</span></p>

 </div>
 
 <div class="refsect1 description" id="refsect1-function.strnatcmp-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>strnatcmp</strong></span>(<span class="methodparam"><span class="type">string</span> <code class="parameter">$string1</code></span>, <span class="methodparam"><span class="type">string</span> <code class="parameter">$string2</code></span>): <span class="type">int</span></div>

  <p class="para rdfs-comment">
   该函数实现了以人类习惯对数字型字符串进行排序的比较算法，这就是“自然顺序”。注意该比较区分大小写。
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.strnatcmp-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>
    
     <dt>
<code class="parameter">string1</code></dt>

     <dd>

      <p class="para">
       第一个字符串。
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">string2</code></dt>

     <dd>

      <p class="para">
       第二个字符串。
      </p>
     </dd>

    
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.strnatcmp-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   与其他字符串比较函数类似，如果 <code class="parameter">string1</code> 小于
   <code class="parameter">string2</code> 返回 <code class="literal">-1</code>；
   如果 <code class="parameter">string1</code>
   大于 <code class="parameter">string2</code>
   返回 <code class="literal">1</code>；如果两者相等，返回 <code class="literal">0</code>。
  </p>
 </div>


 <div class="refsect1 changelog" id="refsect1-function.strnatcmp-changelog">
  <h3 class="title">更新日志</h3>
  <table class="doctable informaltable">
   
    <thead>
     <tr>
      <th>版本</th>
      <th>说明</th>
     </tr>

    </thead>

    <tbody class="tbody">
     <tr>
 <td>8.2.0</td>
 <td>
  现在此函数返回 <code class="literal">-1</code> 或者 <code class="literal">1</code>，之前返回负数或正数。
 </td>
</tr>


    </tbody>
   
  </table>

 </div>


 <div class="refsect1 examples" id="refsect1-function.strnatcmp-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   下面的例子展示了该算法与计算机常规字符串比较算法（<span class="function"><a href="function.strcmp.html" class="function">strcmp()</a></span> 所使用的）的区别：
   <div class="informalexample">
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />$arr1&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$arr2&nbsp;</span><span style="color: #007700">=&nbsp;array(</span><span style="color: #DD0000">"img12.png"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"img10.png"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"img2.png"</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"img1.png"</span><span style="color: #007700">);<br />echo&nbsp;</span><span style="color: #DD0000">"Standard&nbsp;string&nbsp;comparison\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">usort</span><span style="color: #007700">(</span><span style="color: #0000BB">$arr1</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"strcmp"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$arr1</span><span style="color: #007700">);<br />echo&nbsp;</span><span style="color: #DD0000">"\nNatural&nbsp;order&nbsp;string&nbsp;comparison\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">usort</span><span style="color: #007700">(</span><span style="color: #0000BB">$arr2</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"strnatcmp"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$arr2</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <p class="para">以上例程会输出：</p>
    <div class="example-contents screen">
<div class="cdata"><pre>
Standard string comparison
Array
(
    [0] =&gt; img1.png
    [1] =&gt; img10.png
    [2] =&gt; img12.png
    [3] =&gt; img2.png
)

Natural order string comparison
Array
(
    [0] =&gt; img1.png
    [1] =&gt; img2.png
    [2] =&gt; img10.png
    [3] =&gt; img12.png
)
</pre></div>
    </div>
   </div>
   更多信息，参见：Martin Pool 的<a href="https://github.com/sourcefrog/natsort" class="link external">&raquo;&nbsp;自然顺序的字符串比较</a>
   page.
  </p>
 </div>


 <div class="refsect1 seealso" id="refsect1-function.strnatcmp-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="function.preg-match.html" class="function" rel="rdfs-seeAlso">preg_match()</a> - 执行匹配正则表达式</span></li>
    <li class="member"><span class="function"><a href="function.strcasecmp.html" class="function" rel="rdfs-seeAlso">strcasecmp()</a> - 二进制安全比较字符串（不区分大小写）</span></li>
    <li class="member"><span class="function"><a href="function.substr.html" class="function" rel="rdfs-seeAlso">substr()</a> - 返回字符串的子串</span></li>
    <li class="member"><span class="function"><a href="function.stristr.html" class="function" rel="rdfs-seeAlso">stristr()</a> - strstr 函数的忽略大小写版本</span></li>
    <li class="member"><span class="function"><a href="function.strcmp.html" class="function" rel="rdfs-seeAlso">strcmp()</a> - 二进制安全字符串比较</span></li>
    <li class="member"><span class="function"><a href="function.strncmp.html" class="function" rel="rdfs-seeAlso">strncmp()</a> - 二进制安全比较字符串开头的若干个字符</span></li>
    <li class="member"><span class="function"><a href="function.strncasecmp.html" class="function" rel="rdfs-seeAlso">strncasecmp()</a> - 二进制安全比较字符串开头的若干个字符（不区分大小写）</span></li>
    <li class="member"><span class="function"><a href="function.strnatcasecmp.html" class="function" rel="rdfs-seeAlso">strnatcasecmp()</a> - 使用&ldquo;自然顺序&rdquo;算法比较字符串（不区分大小写）</span></li>
    <li class="member"><span class="function"><a href="function.strstr.html" class="function" rel="rdfs-seeAlso">strstr()</a> - 查找字符串的首次出现</span></li>
    <li class="member"><span class="function"><a href="function.natsort.html" class="function" rel="rdfs-seeAlso">natsort()</a> - 用&ldquo;自然排序&rdquo;算法对数组排序</span></li>
    <li class="member"><span class="function"><a href="function.natcasesort.html" class="function" rel="rdfs-seeAlso">natcasesort()</a> - 用&ldquo;自然排序&rdquo;算法对数组进行不区分大小写字母的排序</span></li>
   </ul>
  </p>
 </div>


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